Valuable metals substance flow analysis in high-pressure acid leaching process of laterites

Substance flow analysis (SFA), an analytical tool, was applied to a high-pressure acid leaching (HPAL) process of laterites. The results show that although the HPAL process has become the mainstream process for the treatment of laterites, a large amount of solid waste discharge has caused great harm to the environment and restricted its large-scale development. The annual treatment capacity of laterites by HPAL process is 321×10 4 t, and 300×10 4 t of high-pressure leaching residue, 10×10 4 t of sulfate residue, 1.6×10 4 t of iron and aluminum residue, and 0.08×10 4 t of acid leaching residue are discharged every year. Nickel, cobalt, and manganese are used as the raw materials for the preparation of a precursor, and the masses finally flowing into the precursor preparation process are 2.70×10 4 t/a, 0.24×10 4 t/a, and 0.29×10 4 t/a, respectively, and the proportions are 77.14%, 75.00%, and 13.12%, respectively. Scandium finally flows into the scandium extraction process is 40.00 t/a, and the proportion is 37.70%. A total of 98.11% of iron and 99.86% of aluminum can be selectively removed by the high-pressure acid leaching. Some recommendations for improving emission control and resource recycling for the high-pressure acid leaching process of laterites are put forward in the conclusions of this study.